Refrigerating apparatus



July 28, 1942. J. EVERETTS, JR 2,291,029

REFRIGERATING APPARATUS Filed April 23, 1940 2 Sheets-Sheet 1 A ToRNEYa.

y 1942- J. EVERETTS, JR 2,291,029

- REFRIGERATING APPARATUS Filed April 23, 1940 2 Sheets-Sheet 2 INVENsywmqaa ATTORNEYS Patented July 28, 1942 UNITED STATES PATENT OFFICEREFRIGERATING ArrAnA'rUs John Everetts, Jr., Dayton, Ohio, asslgnor toGeneral Motors Corporation, Dayton, Ohio, a corporation of DelawareApplication April 23, 1940, Serial No. 331,195

9 Claims.

This invention relates to refrigerating apparatus and more particularlyto. an air .con-

ditioning system in which a secondary refrigerant circuit is used forreheating the conditioned-air.

It is common practice to provide a simple refrigerating system forcooling'the air and to control the amount of cooling by starting andstopping the refrigerating system". In a system of this type the airleaving the evaporator is of necessity very cold when the refrigeratingsystem is in operation but is relatively warm when the refrigerationsystem is not in operation. Furthermore, in a system of'this type soonafter the refrigerat- 1 ing apparatus stops, the warm air fiowing overthe evaporator coil tends to reevaporate some of the condensate formedon the evaporator'coil during the cooling cycle whereby the airdischarged into the conditioned space becomes op- Another object of thisinvention is to provide a reheating system which may be readily adaptedto existing refrigerating systems without decreasing the capacity of therefrigerating system.

Still another object of this invention is to provide improved means forcontrolling the rehea system.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accom panyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. l is a diagrammatic showing of a preferred modification in which avolatile refrigerant is used in-the secondary circuit;

Fig. 2 is a diagrammatic view of another modification in which water orthe like may be used as the secondary refrigerant;

Fig. 3 is a diagrammatic view of a further modiflcation showing adifferent type of control; and Fig. 4 is also a diagrammatic viewshowing a still further modified arrangement.

As shown in Fig. 1 I have provided an air cirevaporator I2 andthereafter over the reheat coll it, both of which are disposed withinthe air duct l 5. The refrigerant vaporized in the evaporator l2 may bewithdrawn therefrom by means of any conventional refrigerant compressor.For, purposes of illustration, I have shown a hermetically sealedmotor-compressor unit ii, the motor of which is controlled by aconventional thermostat is which may be placed in the return air duct ordirectly within the conditioned space. The compressed refrigerant. vapordischarged from the compressor l6 flowsthr'ough a heat interchanger l8which is arranged in series with a conventional condenser unit 20.Liquid refrigerant from the condenser 20 is supplied to the evaporator12 through the automatic thermostatic expansion valve 22 which isofconventional construction. As shown in the drawings,

the valve 22 includes the usual thermostatic bulb 20 24 which serves toshut oil the flow of refrigerant to the evaporator when the liquidrefrigerant reaches the outlet of the evaporator.

A secondary volatile refrigeration system which includes the reheat coilM has been provided for transferring heat from the compressed gasflowing through the heat interchanger l8 to the air stream flowing overthe reheat coil ll. This secondary system includes a liquid refrigerantreceiver 26, a thermostatically controlled valve-28 and a heat exchangecoil 30 which serves as an.

evaporator for the secondary system. This secondary system is chargedwith any suitable volatile refrigerant which will evaporate at thetemperatures normally prevailing in the heat interchanger l8 and whichwill be condensed in the reheat coil H by thecold air coming from themain evaporator I2.

The valve 28 is opened and closed in response to the temperature of theair flowing over the bulb 32 placed in the incoming air stream. Valve 28may be of an on-ofi type or it may be a modulating type of valve. Whenthe temperature of the incoming air is excessively high, the valve 28reduces the flow of refrigerant in the secondary, system. When the valve28 is completely closed the cold air leaving the coil I2 will tend tocondense all of the refrigerant vapor in the secondary system and thiscondensed refrigerant will be stored in the receiver 26. Thermostats l8and 32 are so calibrated as to cause the compressor of the primaryrefrigeration system to operate continuously except at such times whenno conculating fan II) which blows air over the main maximum amount ofheat is returned to the air stream at such times when the temperature ofthe air flowing over the bulb 32 indicates that very little cooling isrequired.

The capacity of the secondary system is preferably such thatsubstantially allof the heat removed frorn'the air may be returned tothe air whereby the refrigerating apparatus may be used for removinglarge volumes of moisture from the air without materially reducing thedry bulb temperature of the air in the conditioned space. The maincondenser 20 has 9. capacity suflicient to condense all of the liquidrefrigerant of the primary system at such times when the secondarysystem is not operating as a reheat system. Whenever the secondarysystem is operating, the heat interchanger 18 has the eifect of reducingthe condensing pressure. This results in a more efllcient operation ofthe primary system.

In Fig. 2 I have shown a slightly different modification in which theprimary system is identical with the primary system disclosed in Fig. lbut in which the secondary system employs a non-volatile refrigerant,such as water, which is circulated between a reheat coil Il|,-correspnding to reheat coil M in Fig. 1, and a heat absorbing coil I 30 disposedwithin the heat interchanger It by means of a pump 50 located in theline between the reheat coil Ill and the heat absorbing coil I30. Itshould be noted that like reference characters have been used fordesignating like parts in the various modifications. The pump 50 isarranged to circulate the fluid in the direction of the arrow shown inFig. 2. The fluid leaving the heat absorber I30 discharges into a surgetank 52. The surge tank 52 is provided with. a sight glass 54, anatmospheric vent 55 and a make-up water pipe 58, all of which are ofconventional design and serve their usual functions. The amount ofreheating taking place is controlled by a three-way valve 60 which isadapted to connect the inlet of the pump 50 either to the reheat coil IH or the by-pass 62 which makes it possible to by-pass all of thesecondary refrigerant around the reheat coil whereby no heat is returnedto the air stream. The valve 50 is controlled by means of a dry bulbthermostat 64 located in the incoming air stream or directly within thespace to be conditioned. In order to simplify the disclosure I haveshown no means for controlling the operation of the pump 50 in this orany of the other modifications. It is within the purview of thisinvention, however, to provide further automatic control of the pump 50whereby the pump 50 automatically stops when no reheat whatsoever isrequired.

In Fig. 3 I have shown a modification which is very similar to themodification shown in Fig. 2 except that in place of by-passing thesecondary heat exchange coil I I have provided a by-pass N forby-passing the compressed refrigerant vapor of the primary system aroundthe heat interchanger H8 whenever reheating is not required. The by-passIII is controlled by a three-way valve 12, which in turn is undercontrol of the dry bulb thermostat 14 located in the incoming airstream. The valve 12 may be an on-ofi type of valve or it may be amodulating type of valve.

While I have shown a pump 50 in a modification shown in Fig. 3 it isapparent that in the arrangement shown in Fig. 3 a volatile refrigerantmay be used in the secondary system in which case the pump 50, the surgetank 52 and its associated parts may be dispensed with.

In Fig. 4 I have shown a still further modification in which thesecondary system may employ either a volatile refrigerant or acirculatin liquid. In this modification the amount of reheat iscontrolled by means of a three-way valve 80 which is controlled by drybulb thermostat 84 located in the incoming air stream or directly withinthe enclosure to be conditioned. This three-way valve 80 is arranged soas to direct the flow of secondary refrigerant either through the reheatcoil I 4 or through the coil 88 which is cooled by the same means whichcools the main condenser 20. The coil 88 and the condenser 20 may becooled by means of any conventional cooling medium. For purposes ofillustration, I have shown a fan unit 90 for circulating a stream of airover the coil 88 and the condenser Zll. By virtue of this arrangementthe secondary system at all times assists in lowering the condensingpressure. In the modification shown in Fig. 4 the pump 5|! may beomitted when using a volatile refrigerant in the secondary system.

While I have shown dry bulb control instruments only throughout thisapplication, it is within the purview of thisinvention to substituteother types of control instruments such as wet bulb, a combination ofwet and dry bulb, humidity, or effective temperature instruments for thedry bulb instruments shown. It is also within the purview of thisinvention to arrange the instruments so as to be responsive to thedischarge air temperatures or to the temperatures of the air outside thespace to be conditioned.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. In combination, a primary evaporator, a primary compressor, a primarycondenser, a heat interchanger having a plurality of separate passages,primary refrigerant flow connections between said primary evaporator,primary compressor, primary condenser and one passage of said heatinterchanger, a secondary condenser in refrigerant flow relationshipwith another passage of said heat interchanger, means for circulatingair to be conditioned in thermal exchange relationship with said primaryevaporator and thereafter in thermal exchange relationship with saidsecondary condenser, and means for bypassing the flow of secondaryrefrigerant around said secondary condenser.

2. In combination, a primary evaporator, a primary compressor, a primarycondenser, a heat interchanger having a plurality of separate passages,primary refrigerant flow connections between said primary evaporator,primary compressor, primary condenser and one passage of said heatinterchanger, a secondary condenser in refrigerant flow relationshipwith another passage of said heat interchanger, means for circulatingair to be conditioned in thermal exchange relationship with said primaryevaporator and thereafter in thermal exchange relationship with saidsecondary condenser, means for bypassing the'flow of secondaryrefrigerant around said secondary condenser, and means responsive to thedry bulb temperature for controlling said by-pass means.

3. In combination,'a primary evaporator, a

primary compressor, a heat interchanger having a plurality of passages,a primary condenser, primary refrigerant flow connections between saidprimary evaporator, said primary compressor, a first passage of saidheat interchanger and said primary condenser, means for circulating airto be conditioned in thermal exchange relationship with said primaryevaporator, a reheat coil in thermal exchange relationship with the aircooled by said primary evaporator, a surge tank, means for circulating asecondary fluid through said reheat coil, a second passage of said heatinterchanger and said surge tank in series, and means for by-passingsaid reheat coil.

4. In combination, a primary evaporator, a primary compressor, a heatinterchanger having a plurality of passages, a primary condenser,primary refrigerant flow connections between said primary evaporator,said primary compressor, a first passage of said heat interchanger andsaid primary condenser, means for circulating air to be conditioned inthermal exchange relationship with said primary evaporator, a reheatcoil in thermal exchange relationship with the air cooled by saidprimary evaporator, a surge tank, means for circulating a secondaryfluid through said reheat coil, a second passage of said heatinterchanger and said surge tank in series, means for by-passing saidreheat coil, and means responsive to the dry bulb temperature of the airto be conditioned controlling said by-pass.

5. In combination, a primary evaporator, a primary compressor, a heatinterchanger having a plurality of passages, a primary condenser,primary refrigerant flow connections between said primary evaporator,said primary compressor, a first passage of said heat interchanger andsaid primary condenser, means for circulating air to be conditioned inthermal exchange relationship with said primary evaporator, a reheatcoil in thermal exchange relationship with the air cooled by saidprimary evaporator, a surge tank, means for circulating a secondaryfluid through said reheat coil, a second passage of said heatinterchanger and said surge tank in series, means for by-passing saidreheat coil, means responsive to the dry bulb temperature of the air tobe conditioned controlling said by-pass, means for ventme said surgetank, and means for adding makeup fluid to said secondary circulatingsystem.

6. In combination, a primary evaporator, a primary compressor, a heatinterchanger, a pri mary condenser, refrigerant flow connections betweensaid primary evaporator, primary compressor, heat interchanger andprimary condenser, means for circulating air to be conditioned inthermal exchange relationship with said primary evaporator, means forflowing a cooling fluidover said primary condenser, secondary condensermeans having one portion arranged in thermal exchange relationship withthe air flowing over said primary evaporator and a second portionarranged to be cooled by the condenser cooling fluid, and secondaryevaporator means in refrigerant flow relationship with said secondarycondenser means, said secondary evaporator means comprising meansforming one portion of said heat interchanger.

means for circulating air to be conditioned in thermal exchangerelationship with said primary evaporator, means for flowing a coolingfluid over said primary condenser, secondary condenser means having oneportion arranged in thermal exchange relationship with the air flowingover said primary evaporator and a second portion arranged to be cooledby the condenser cooling fluid, secondary evaporator means inrefrigerant flow relationship with said secondary condenser means, saidsecondary evaporator means comprising means forming one portion of saidheat interchanger, and means for controlling the flow of secondaryrefrigerant through one of said portions.

8. In combination, a primary evaporator, a primary compressor, a heatinterchanger, a primary condenser, refrigerant flow connections betweensaid primary evaporator, primary compressor, heat interchanger andprimary condenser, means for circulating air to be conditioned inthermal exchange relationship with said primary evaporator, means forflowing a cooling fluid over said primary condenser, secondary condensermeans having one portion arranged in thermal exchange relationship withthe air flowing over said primary evaporator and a second portionarranged to be cooled by the condenser cooling fluid, secondaryevaporator means in refrigerant flow relationshi with said secondarycondenser means, said secondary evaporator means comprising meansforming one portion of said heat interchanger, and means for controllingthe flow of secondary refrigerant through one of said portions, saidlast named means comprising a thermostat responsive to the temperatureof the air.

9. In combination, a closed primary refrigerant system including a heatdissipating portion and a heat absorbing portion, a closed secondaryrefrigerant system including a condenser and an evaporator, saidevaporator being in heat exchange relation with the heat dissipatingportion of the primary refrigerant system, means for circulating air tobe conditioned in thermal relationship with said primary evaporator andthereafter in thermal exchange relationship with said secondarycondenser, and means for bypassing the flow of secondary refrigerantaround said secondary condenser.

JOHN EVERE'I'I'S, JR.

